Barium/air contrast colonic radiography (Computerised Tomography (CT) colonography) and virtual colonoscopy are radiographic techniques aiming at imaging the colon for anatomical appearance, endoluminal lesions or mucosal abnormalities. In both procedures, a small, flexible tube is passed few inches into the rectum, and a small balloon is inflated to allow air to be gently pumped into the colon using a hand-held squeeze bulb. Sometimes, an electronic pump is used to deliver carbon dioxide gas into the colon. The purpose of the gas is to distend the colon to eliminate any folds or wrinkles that might obscure polyps or other lesions from the physician's view. In the case of colonic radiography, barium (a radio-opaque heavy metal) is also pumped in the rectum, and this barium covers the inner-lining of the colon creating a contrast with the intra-abdominal organs. Mucosal and endo-luminal abnormalities can be depicted and diagnostically interpreted by radiologists.
In the case of Virtual colonoscopy, CT colonography uses CT scanning to obtain an interior view of the colon (the large intestine) that is ordinarily only seen with an endoscope inserted into the rectum. CT imaging uses special x-ray equipment to produce multiple images or pictures of the inside of the body and a computer to join them together in cross-sectional views of the area being studied. The images can then be examined on a computer monitor or printed.
Colonoscopy is a test that allows physicians to look at the interior lining of the large intestine (rectum and colon) through a thin, flexible viewing instrument called a colonoscope. A colonoscopy helps detect ulcers, erosions, polyps, tumors, and areas of inflammation or bleeding. During a colonoscopy, tissue samples can be collected (biopsies) and abnormal growths can be removed. Colonoscopy can also be sued as a screening test to identify and remove precancerous and cancerous growths in the colon or rectum.
Before this test, the colon needs to be cleaned out. Colon prep takes 1 to 2 days depending on the preferred prep selected.
Endoscopical or virtual Colonoscopy is usually a painful procedure. Air distension of the colon wall, stretching of the mesenteric attachment and colonic, spastic contractions are usually the causative factors for the pain experienced by the patients. A better tolerability of nociceptive air distension of the colonic wall, and the fewer spastic contractions allow for a reduced time to reach the caecum and successfully complete the colonic examination, for a better patient's tolerance of the procedure, and for a better acceptance of repeated procedures.
No specific guidelines exist to regulate the use of analgesic modalities in the performance of virtual colonoscopy, barium/air contrast colonography or endoscopical colonoscopy.
For endoscopical colonoscopy, it is therefore not surprising to find an impressive list of proposed analgesia and/or sedation modalities that are used in different countries and in different investigation units i.e. hospital-based or out-patient clinic facilities. This list encompasses general anesthesia performed by anesthesiologists, sedo-analgesia performed by anesthesiologists or gastroenterologists, sedo-analgesia performed by a trained nurse. Sedo-analgesia is the most frequently used type of sedation during colonoscopy worldwide. It is usually achieved by combining midazolam with propofol and/or fentanyl or pethidine.
When these proposed pharmacological modalities are administered, a constant patient monitoring during and after the procedure is required to avoid risks of cardio-vascular or respiratory complications, thereby generating increased costs in time, specialized personnel and specialized space allocation. These drawbacks led to the evaluation of the risks and benefits of performing endoscopical colonoscopy with or without sedation. (J. Clin Gastroenterology 1998, June:24(4):279-282). In summary it is now well accepted that it is feasible and safe to perform a successful colonoscopy without sedation, and this usually does not undermine the willingness of patients to undergo a similar procedure in the future.
It would therefore be highly desirable to be provided with a method that would be an alternative to the previously proposed methods. It would therefore be also highly desirable to be provided with a method that would permit to overcome at least some of the prior art drawbacks.